In the related art, a surface inspection system typically includes a camera system which is utilized for scanning moving surfaces, such as web production lines, in order to monitor and analyze the moving surface for quality control purposes. For instance, a moving surface such as a continuous production line of photographic paper may be passed in front of the camera system for the purpose of scanning the photographic paper for defects. The defects could include dark spots on the photographic paper. In this example, the related art typically has at least one camera connected to a processing unit such as a computer mainframe. The camera, which is placed in a position to scan the moving surface, provides data about the scan, generally in the form of a video signal. The camera is positioned to scan the moving surface according to the field of view provided by the camera. Accurate inspection requires proper alignment, relative to a target surface, of the field of view of the scanning camera as well as an illumination source utilized by the camera system.
Existing methods of establishing and verifying optical front end inspection geometry rely on time-consuming empirical approaches to achieve camera and illumination source alignment relative to the target surface. For instance, an inspection system for scanning a web production line with a target surface that is wider than the field of view of one camera has a plurality of cameras with an overlapping field of view. Related art in this instance "points" each of the plurality of cameras to a target area of the product to be scanned without verifying the precise field of view that is in fact covered by a particular camera. As a result, small areas of the product to be scanned may in fact be missed, resulting in an inferior inspection. Alternatively, a larger area of the product to be scanned may be double scanned by an excessive overlap of the field of view of the plurality of cameras, resulting in excessive equipment being used for the inspection.
Another problem in the related art is verifying that the illumination source necessary for camera inspection is in fact aligned precisely at the same target area of the product to be scanned that a particular field of view of a camera is aligned to. Typically, inspection of a product is performed across a large roller. Changing the diameter of the roller, for example with a necessary regrinding of the roller, changes the positioning the product to be scanned. This change in position requires a change in positioning of the camera and or light source which is typically accomplished by the previously mentioned time-consuming empirical approaches.